Flu levels continue to decrease

Thursday 16th February 2017
Influenza activity continued to decrease during the week ending February 12th 2017. The GP influenza-like illness (ILI) rate decreased to 15.2 per 100,000, compared to the updated rate of 25.2 per 100,000 during the previous week. The ILI rate is now below the Irish baseline threshold (18.3/100,000), for the first time since early December. Influenza activity peaked during the first week of January.  It is expected that influenza activity will continue to decline further in the coming weeks.
 
Influenza A(H3N2) remains the predominant virus circulating, at low levels, with those aged 65 years and older most affected from severe influenza. Norovirus continues to circulate and also impacts on the elderly in terms of morbidity (outbreaks in residential care facilities and acute hospitals).
Influenza hospitalisations and outbreaks continue to be reported at low levels. To date this season, 1193 hospitalised influenza cases, 38 ICU flu cases and 100 acute respiratory infections/influenza outbreaks (89 in residential care facilities/community hospitals and 11 in acute hospitals) have been reported to HPSC. 
 
Sixty-six deaths associated with influenza have been reported to HPSC to date, the majority of these were aged 65 years and older. Excess deaths from all causes in those aged 65 years and older were reported during December and January. Seasons where influenza A(H3N2) is the predominant virus in circulation usually result in excess deaths in those aged 65 years and older. 

Genetic analysis was undertaken by the National Virus Reference Laboratory (NVRL) on a selection of influenza samples from patients. The majority (over 70%) of the sequenced specimens of circulating influenza strains show a match to the vaccine strain.

Influenza vaccines provide seasonally variable protection of 40-90% against influenza in persons less than 65 years of age. Protective efficacy against infection is lower in the elderly. Effectiveness is always partial and the use of antivirals for the treatment of laboratory-confirmed or probable cases of influenza should be considered for vaccinated and non-vaccinated patients at risk.
Last updated on: 17 / 02 / 2017